includes/db/DatabasePostgres.php

   1 <?php
   2 /**
   3  * This is the Postgres database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23
  24 class PostgresField implements Field {
  25         private $name, $tablename, $type, $nullable, $max_length, $deferred, $deferrable, $conname,
  26                 $has_default, $default;
  27
  28         /**
  29          * @param IDatabase $db
  30          * @param string $table
  31          * @param string $field
  32          * @return null|PostgresField
  33          */
  34         static function fromText( $db, $table, $field ) {
  35                 $q = <<<SQL
  36 SELECT
  37  attnotnull, attlen, conname AS conname,
  38  atthasdef,
  39  adsrc,
  40  COALESCE(condeferred, 'f') AS deferred,
  41  COALESCE(condeferrable, 'f') AS deferrable,
  42  CASE WHEN typname = 'int2' THEN 'smallint'
  43   WHEN typname = 'int4' THEN 'integer'
  44   WHEN typname = 'int8' THEN 'bigint'
  45   WHEN typname = 'bpchar' THEN 'char'
  46  ELSE typname END AS typname
  47 FROM pg_class c
  48 JOIN pg_namespace n ON (n.oid = c.relnamespace)
  49 JOIN pg_attribute a ON (a.attrelid = c.oid)
  50 JOIN pg_type t ON (t.oid = a.atttypid)
  51 LEFT JOIN pg_constraint o ON (o.conrelid = c.oid AND a.attnum = ANY(o.conkey) AND o.contype = 'f')
  52 LEFT JOIN pg_attrdef d on c.oid=d.adrelid and a.attnum=d.adnum
  53 WHERE relkind = 'r'
  54 AND nspname=%s
  55 AND relname=%s
  56 AND attname=%s;
  57 SQL;
  58
  59                 $table = $db->tableName( $table, 'raw' );
  60                 $res = $db->query(
  61                         sprintf( $q,
  62                                 $db->addQuotes( $db->getCoreSchema() ),
  63                                 $db->addQuotes( $table ),
  64                                 $db->addQuotes( $field )
  65                         )
  66                 );
  67                 $row = $db->fetchObject( $res );
  68                 if ( !$row ) {
  69                         return null;
  70                 }
  71                 $n = new PostgresField;
  72                 $n->type = $row->typname;
  73                 $n->nullable = ( $row->attnotnull == 'f' );
  74                 $n->name = $field;
  75                 $n->tablename = $table;
  76                 $n->max_length = $row->attlen;
  77                 $n->deferrable = ( $row->deferrable == 't' );
  78                 $n->deferred = ( $row->deferred == 't' );
  79                 $n->conname = $row->conname;
  80                 $n->has_default = ( $row->atthasdef === 't' );
  81                 $n->default = $row->adsrc;
  82
  83                 return $n;
  84         }
  85
  86         function name() {
  87                 return $this->name;
  88         }
  89
  90         function tableName() {
  91                 return $this->tablename;
  92         }
  93
  94         function type() {
  95                 return $this->type;
  96         }
  97
  98         function isNullable() {
  99                 return $this->nullable;
 100         }
 101
 102         function maxLength() {
 103                 return $this->max_length;
 104         }
 105
 106         function is_deferrable() {
 107                 return $this->deferrable;
 108         }
 109
 110         function is_deferred() {
 111                 return $this->deferred;
 112         }
 113
 114         function conname() {
 115                 return $this->conname;
 116         }
 117
 118         /**
 119          * @since 1.19
 120          * @return bool|mixed
 121          */
 122         function defaultValue() {
 123                 if ( $this->has_default ) {
 124                         return $this->default;
 125                 } else {
 126                         return false;
 127                 }
 128         }
 129 }
 130
 131 /**
 132  * Manage savepoints within a transaction
 133  * @ingroup Database
 134  * @since 1.19
 135  */
 136 class SavepointPostgres {
 137         /** @var DatabasePostgres Establish a savepoint within a transaction */
 138         protected $dbw;
 139         protected $id;
 140         protected $didbegin;
 141
 142         /**
 143          * @param IDatabase $dbw
 144          * @param int $id
 145          */
 146         public function __construct( $dbw, $id ) {
 147                 $this->dbw = $dbw;
 148                 $this->id = $id;
 149                 $this->didbegin = false;
 150                 /* If we are not in a transaction, we need to be for savepoint trickery */
 151                 if ( !$dbw->trxLevel() ) {
 152                         $dbw->begin( "FOR SAVEPOINT", DatabasePostgres::TRANSACTION_INTERNAL );
 153                         $this->didbegin = true;
 154                 }
 155         }
 156
 157         public function __destruct() {
 158                 if ( $this->didbegin ) {
 159                         $this->dbw->rollback();
 160                         $this->didbegin = false;
 161                 }
 162         }
 163
 164         public function commit() {
 165                 if ( $this->didbegin ) {
 166                         $this->dbw->commit();
 167                         $this->didbegin = false;
 168                 }
 169         }
 170
 171         protected function query( $keyword, $msg_ok, $msg_failed ) {
 172                 if ( $this->dbw->doQuery( $keyword . " " . $this->id ) !== false ) {
 173                 } else {
 174                         wfDebug( sprintf( $msg_failed, $this->id ) );
 175                 }
 176         }
 177
 178         public function savepoint() {
 179                 $this->query( "SAVEPOINT",
 180                         "Transaction state: savepoint \"%s\" established.\n",
 181                         "Transaction state: establishment of savepoint \"%s\" FAILED.\n"
 182                 );
 183         }
 184
 185         public function release() {
 186                 $this->query( "RELEASE",
 187                         "Transaction state: savepoint \"%s\" released.\n",
 188                         "Transaction state: release of savepoint \"%s\" FAILED.\n"
 189                 );
 190         }
 191
 192         public function rollback() {
 193                 $this->query( "ROLLBACK TO",
 194                         "Transaction state: savepoint \"%s\" rolled back.\n",
 195                         "Transaction state: rollback of savepoint \"%s\" FAILED.\n"
 196                 );
 197         }
 198
 199         public function __toString() {
 200                 return (string)$this->id;
 201         }
 202 }
 203
 204 /**
 205  * @ingroup Database
 206  */
 207 class DatabasePostgres extends DatabaseBase {
 208         /** @var resource */
 209         protected $mLastResult = null;
 210
 211         /** @var int The number of rows affected as an integer */
 212         protected $mAffectedRows = null;
 213
 214         /** @var int */
 215         private $mInsertId = null;
 216
 217         /** @var float|string */
 218         private $numericVersion = null;
 219
 220         /** @var string Connect string to open a PostgreSQL connection */
 221         private $connectString;
 222
 223         /** @var string */
 224         private $mCoreSchema;
 225
 226         function getType() {
 227                 return 'postgres';
 228         }
 229
 230         function implicitGroupby() {
 231                 return false;
 232         }
 233
 234         function implicitOrderby() {
 235                 return false;
 236         }
 237
 238         function hasConstraint( $name ) {
 239                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
 240                         "WHERE c.connamespace = n.oid AND conname = '" .
 241                         pg_escape_string( $this->mConn, $name ) . "' AND n.nspname = '" .
 242                         pg_escape_string( $this->mConn, $this->getCoreSchema() ) . "'";
 243                 $res = $this->doQuery( $sql );
 244
 245                 return $this->numRows( $res );
 246         }
 247
 248         /**
 249          * Usually aborts on failure
 250          * @param string $server
 251          * @param string $user
 252          * @param string $password
 253          * @param string $dbName
 254          * @throws DBConnectionError|Exception
 255          * @return resource|bool|null
 256          */
 257         function open( $server, $user, $password, $dbName ) {
 258                 # Test for Postgres support, to avoid suppressed fatal error
 259                 if ( !function_exists( 'pg_connect' ) ) {
 260                         throw new DBConnectionError(
 261                                 $this,
 262                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
 263                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
 264                                 "webserver and database)\n"
 265                         );
 266                 }
 267
 268                 global $wgDBport;
 269
 270                 if ( !strlen( $user ) ) { # e.g. the class is being loaded
 271                         return null;
 272                 }
 273
 274                 $this->mServer = $server;
 275                 $port = $wgDBport;
 276                 $this->mUser = $user;
 277                 $this->mPassword = $password;
 278                 $this->mDBname = $dbName;
 279
 280                 $connectVars = [
 281                         'dbname' => $dbName,
 282                         'user' => $user,
 283                         'password' => $password
 284                 ];
 285                 if ( $server != false && $server != '' ) {
 286                         $connectVars['host'] = $server;
 287                 }
 288                 if ( $port != false && $port != '' ) {
 289                         $connectVars['port'] = $port;
 290                 }
 291                 if ( $this->mFlags & DBO_SSL ) {
 292                         $connectVars['sslmode'] = 1;
 293                 }
 294
 295                 $this->connectString = $this->makeConnectionString( $connectVars, PGSQL_CONNECT_FORCE_NEW );
 296                 $this->close();
 297                 $this->installErrorHandler();
 298
 299                 try {
 300                         $this->mConn = pg_connect( $this->connectString );
 301                 } catch ( Exception $ex ) {
 302                         $this->restoreErrorHandler();
 303                         throw $ex;
 304                 }
 305
 306                 $phpError = $this->restoreErrorHandler();
 307
 308                 if ( !$this->mConn ) {
 309                         wfDebug( "DB connection error\n" );
 310                         wfDebug( "Server: $server, Database: $dbName, User: $user, Password: " .
 311                                 substr( $password, 0, 3 ) . "...\n" );
 312                         wfDebug( $this->lastError() . "\n" );
 313                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 314                 }
 315
 316                 $this->mOpened = true;
 317
 318                 global $wgCommandLineMode;
 319                 # If called from the command-line (e.g. importDump), only show errors
 320                 if ( $wgCommandLineMode ) {
 321                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 322                 }
 323
 324                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 325                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 326                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 327                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 328                 if ( $this->getServerVersion() >= 9.0 ) {
 329                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 330                 }
 331
 332                 global $wgDBmwschema;
 333                 $this->determineCoreSchema( $wgDBmwschema );
 334
 335                 return $this->mConn;
 336         }
 337
 338         /**
 339          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 340          * DB name doesn't match the open connection, open a new one
 341          * @param string $db
 342          * @return bool
 343          */
 344         function selectDB( $db ) {
 345                 if ( $this->mDBname !== $db ) {
 346                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 347                 } else {
 348                         return true;
 349                 }
 350         }
 351
 352         function makeConnectionString( $vars ) {
 353                 $s = '';
 354                 foreach ( $vars as $name => $value ) {
 355                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 356                 }
 357
 358                 return $s;
 359         }
 360
 361         /**
 362          * Closes a database connection, if it is open
 363          * Returns success, true if already closed
 364          * @return bool
 365          */
 366         protected function closeConnection() {
 367                 return pg_close( $this->mConn );
 368         }
 369
 370         public function doQuery( $sql ) {
 371                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 372                 // Clear previously left over PQresult
 373                 while ( $res = pg_get_result( $this->mConn ) ) {
 374                         pg_free_result( $res );
 375                 }
 376                 if ( pg_send_query( $this->mConn, $sql ) === false ) {
 377                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 378                 }
 379                 $this->mLastResult = pg_get_result( $this->mConn );
 380                 $this->mAffectedRows = null;
 381                 if ( pg_result_error( $this->mLastResult ) ) {
 382                         return false;
 383                 }
 384
 385                 return $this->mLastResult;
 386         }
 387
 388         protected function dumpError() {
 389                 $diags = [
 390                         PGSQL_DIAG_SEVERITY,
 391                         PGSQL_DIAG_SQLSTATE,
 392                         PGSQL_DIAG_MESSAGE_PRIMARY,
 393                         PGSQL_DIAG_MESSAGE_DETAIL,
 394                         PGSQL_DIAG_MESSAGE_HINT,
 395                         PGSQL_DIAG_STATEMENT_POSITION,
 396                         PGSQL_DIAG_INTERNAL_POSITION,
 397                         PGSQL_DIAG_INTERNAL_QUERY,
 398                         PGSQL_DIAG_CONTEXT,
 399                         PGSQL_DIAG_SOURCE_FILE,
 400                         PGSQL_DIAG_SOURCE_LINE,
 401                         PGSQL_DIAG_SOURCE_FUNCTION
 402                 ];
 403                 foreach ( $diags as $d ) {
 404                         wfDebug( sprintf( "PgSQL ERROR(%d): %s\n",
 405                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 406                 }
 407         }
 408
 409         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 410                 if ( $tempIgnore ) {
 411                         /* Check for constraint violation */
 412                         if ( $errno === '23505' ) {
 413                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 414
 415                                 return;
 416                         }
 417                 }
 418                 /* Transaction stays in the ERROR state until rolled back */
 419                 if ( $this->mTrxLevel ) {
 420                         $ignore = $this->ignoreErrors( true );
 421                         $this->rollback( __METHOD__ );
 422                         $this->ignoreErrors( $ignore );
 423                 }
 424                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 425         }
 426
 427         function queryIgnore( $sql, $fname = __METHOD__ ) {
 428                 return $this->query( $sql, $fname, true );
 429         }
 430
 431         /**
 432          * @param stdClass|ResultWrapper $res
 433          * @throws DBUnexpectedError
 434          */
 435         function freeResult( $res ) {
 436                 if ( $res instanceof ResultWrapper ) {
 437                         $res = $res->result;
 438                 }
 439                 MediaWiki\suppressWarnings();
 440                 $ok = pg_free_result( $res );
 441                 MediaWiki\restoreWarnings();
 442                 if ( !$ok ) {
 443                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 444                 }
 445         }
 446
 447         /**
 448          * @param ResultWrapper|stdClass $res
 449          * @return stdClass
 450          * @throws DBUnexpectedError
 451          */
 452         function fetchObject( $res ) {
 453                 if ( $res instanceof ResultWrapper ) {
 454                         $res = $res->result;
 455                 }
 456                 MediaWiki\suppressWarnings();
 457                 $row = pg_fetch_object( $res );
 458                 MediaWiki\restoreWarnings();
 459                 # @todo FIXME: HACK HACK HACK HACK debug
 460
 461                 # @todo hashar: not sure if the following test really trigger if the object
 462                 #          fetching failed.
 463                 if ( pg_last_error( $this->mConn ) ) {
 464                         throw new DBUnexpectedError(
 465                                 $this,
 466                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 467                         );
 468                 }
 469
 470                 return $row;
 471         }
 472
 473         function fetchRow( $res ) {
 474                 if ( $res instanceof ResultWrapper ) {
 475                         $res = $res->result;
 476                 }
 477                 MediaWiki\suppressWarnings();
 478                 $row = pg_fetch_array( $res );
 479                 MediaWiki\restoreWarnings();
 480                 if ( pg_last_error( $this->mConn ) ) {
 481                         throw new DBUnexpectedError(
 482                                 $this,
 483                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 484                         );
 485                 }
 486
 487                 return $row;
 488         }
 489
 490         function numRows( $res ) {
 491                 if ( $res instanceof ResultWrapper ) {
 492                         $res = $res->result;
 493                 }
 494                 MediaWiki\suppressWarnings();
 495                 $n = pg_num_rows( $res );
 496                 MediaWiki\restoreWarnings();
 497                 if ( pg_last_error( $this->mConn ) ) {
 498                         throw new DBUnexpectedError(
 499                                 $this,
 500                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 501                         );
 502                 }
 503
 504                 return $n;
 505         }
 506
 507         function numFields( $res ) {
 508                 if ( $res instanceof ResultWrapper ) {
 509                         $res = $res->result;
 510                 }
 511
 512                 return pg_num_fields( $res );
 513         }
 514
 515         function fieldName( $res, $n ) {
 516                 if ( $res instanceof ResultWrapper ) {
 517                         $res = $res->result;
 518                 }
 519
 520                 return pg_field_name( $res, $n );
 521         }
 522
 523         /**
 524          * Return the result of the last call to nextSequenceValue();
 525          * This must be called after nextSequenceValue().
 526          *
 527          * @return int|null
 528          */
 529         function insertId() {
 530                 return $this->mInsertId;
 531         }
 532
 533         /**
 534          * @param mixed $res
 535          * @param int $row
 536          * @return bool
 537          */
 538         function dataSeek( $res, $row ) {
 539                 if ( $res instanceof ResultWrapper ) {
 540                         $res = $res->result;
 541                 }
 542
 543                 return pg_result_seek( $res, $row );
 544         }
 545
 546         function lastError() {
 547                 if ( $this->mConn ) {
 548                         if ( $this->mLastResult ) {
 549                                 return pg_result_error( $this->mLastResult );
 550                         } else {
 551                                 return pg_last_error();
 552                         }
 553                 } else {
 554                         return 'No database connection';
 555                 }
 556         }
 557
 558         function lastErrno() {
 559                 if ( $this->mLastResult ) {
 560                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 561                 } else {
 562                         return false;
 563                 }
 564         }
 565
 566         function affectedRows() {
 567                 if ( !is_null( $this->mAffectedRows ) ) {
 568                         // Forced result for simulated queries
 569                         return $this->mAffectedRows;
 570                 }
 571                 if ( empty( $this->mLastResult ) ) {
 572                         return 0;
 573                 }
 574
 575                 return pg_affected_rows( $this->mLastResult );
 576         }
 577
 578         /**
 579          * Estimate rows in dataset
 580          * Returns estimated count, based on EXPLAIN output
 581          * This is not necessarily an accurate estimate, so use sparingly
 582          * Returns -1 if count cannot be found
 583          * Takes same arguments as Database::select()
 584          *
 585          * @param string $table
 586          * @param string $vars
 587          * @param string $conds
 588          * @param string $fname
 589          * @param array $options
 590          * @return int
 591          */
 592         function estimateRowCount( $table, $vars = '*', $conds = '',
 593                 $fname = __METHOD__, $options = []
 594         ) {
 595                 $options['EXPLAIN'] = true;
 596                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 597                 $rows = -1;
 598                 if ( $res ) {
 599                         $row = $this->fetchRow( $res );
 600                         $count = [];
 601                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 602                                 $rows = (int)$count[1];
 603                         }
 604                 }
 605
 606                 return $rows;
 607         }
 608
 609         /**
 610          * Returns information about an index
 611          * If errors are explicitly ignored, returns NULL on failure
 612          *
 613          * @param string $table
 614          * @param string $index
 615          * @param string $fname
 616          * @return bool|null
 617          */
 618         function indexInfo( $table, $index, $fname = __METHOD__ ) {
 619                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 620                 $res = $this->query( $sql, $fname );
 621                 if ( !$res ) {
 622                         return null;
 623                 }
 624                 foreach ( $res as $row ) {
 625                         if ( $row->indexname == $this->indexName( $index ) ) {
 626                                 return $row;
 627                         }
 628                 }
 629
 630                 return false;
 631         }
 632
 633         /**
 634          * Returns is of attributes used in index
 635          *
 636          * @since 1.19
 637          * @param string $index
 638          * @param bool|string $schema
 639          * @return array
 640          */
 641         function indexAttributes( $index, $schema = false ) {
 642                 if ( $schema === false ) {
 643                         $schema = $this->getCoreSchema();
 644                 }
 645                 /*
 646                  * A subquery would be not needed if we didn't care about the order
 647                  * of attributes, but we do
 648                  */
 649                 $sql = <<<__INDEXATTR__
 650
 651                         SELECT opcname,
 652                                 attname,
 653                                 i.indoption[s.g] as option,
 654                                 pg_am.amname
 655                         FROM
 656                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 657                                         FROM
 658                                                 pg_index isub
 659                                         JOIN pg_class cis
 660                                                 ON cis.oid=isub.indexrelid
 661                                         JOIN pg_namespace ns
 662                                                 ON cis.relnamespace = ns.oid
 663                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 664                                 pg_attribute,
 665                                 pg_opclass opcls,
 666                                 pg_am,
 667                                 pg_class ci
 668                                 JOIN pg_index i
 669                                         ON ci.oid=i.indexrelid
 670                                 JOIN pg_class ct
 671                                         ON ct.oid = i.indrelid
 672                                 JOIN pg_namespace n
 673                                         ON ci.relnamespace = n.oid
 674                                 WHERE
 675                                         ci.relname='$index' AND n.nspname='$schema'
 676                                         AND     attrelid = ct.oid
 677                                         AND     i.indkey[s.g] = attnum
 678                                         AND     i.indclass[s.g] = opcls.oid
 679                                         AND     pg_am.oid = opcls.opcmethod
 680 __INDEXATTR__;
 681                 $res = $this->query( $sql, __METHOD__ );
 682                 $a = [];
 683                 if ( $res ) {
 684                         foreach ( $res as $row ) {
 685                                 $a[] = [
 686                                         $row->attname,
 687                                         $row->opcname,
 688                                         $row->amname,
 689                                         $row->option ];
 690                         }
 691                 } else {
 692                         return null;
 693                 }
 694
 695                 return $a;
 696         }
 697
 698         function indexUnique( $table, $index, $fname = __METHOD__ ) {
 699                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 700                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 701                         $this->strencode( $this->indexName( $index ) ) .
 702                         ")'";
 703                 $res = $this->query( $sql, $fname );
 704                 if ( !$res ) {
 705                         return null;
 706                 }
 707
 708                 return $res->numRows() > 0;
 709         }
 710
 711         /**
 712          * Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 713          * to the parent function to get the actual SQL text.
 714          *
 715          * In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 716          * can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to do
 717          * so causes a DB error. This wrapper checks which tables can be locked and adjusts it accordingly.
 718          *
 719          * MySQL uses "ORDER BY NULL" as an optimization hint, but that syntax is illegal in PostgreSQL.
 720          * @see DatabaseBase::selectSQLText
 721          */
 722         function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
 723                 $options = [], $join_conds = []
 724         ) {
 725                 if ( is_array( $options ) ) {
 726                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 727                         if ( $forUpdateKey !== false && $join_conds ) {
 728                                 unset( $options[$forUpdateKey] );
 729
 730                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 731                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 732                                                 $options['FOR UPDATE'][] = $table_cond;
 733                                         }
 734                                 }
 735                         }
 736
 737                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 738                                 unset( $options['ORDER BY'] );
 739                         }
 740                 }
 741
 742                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 743         }
 744
 745         /**
 746          * INSERT wrapper, inserts an array into a table
 747          *
 748          * $args may be a single associative array, or an array of these with numeric keys,
 749          * for multi-row insert (Postgres version 8.2 and above only).
 750          *
 751          * @param string $table Name of the table to insert to.
 752          * @param array $args Items to insert into the table.
 753          * @param string $fname Name of the function, for profiling
 754          * @param array|string $options String or array. Valid options: IGNORE
 755          * @return bool Success of insert operation. IGNORE always returns true.
 756          */
 757         function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 758                 if ( !count( $args ) ) {
 759                         return true;
 760                 }
 761
 762                 $table = $this->tableName( $table );
 763                 if ( !isset( $this->numericVersion ) ) {
 764                         $this->getServerVersion();
 765                 }
 766
 767                 if ( !is_array( $options ) ) {
 768                         $options = [ $options ];
 769                 }
 770
 771                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 772                         $multi = true;
 773                         $keys = array_keys( $args[0] );
 774                 } else {
 775                         $multi = false;
 776                         $keys = array_keys( $args );
 777                 }
 778
 779                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 780                 $savepoint = null;
 781                 if ( in_array( 'IGNORE', $options ) ) {
 782                         $savepoint = new SavepointPostgres( $this, 'mw' );
 783                         $olde = error_reporting( 0 );
 784                         // For future use, we may want to track the number of actual inserts
 785                         // Right now, insert (all writes) simply return true/false
 786                         $numrowsinserted = 0;
 787                 }
 788
 789                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 790
 791                 if ( $multi ) {
 792                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 793                                 $first = true;
 794                                 foreach ( $args as $row ) {
 795                                         if ( $first ) {
 796                                                 $first = false;
 797                                         } else {
 798                                                 $sql .= ',';
 799                                         }
 800                                         $sql .= '(' . $this->makeList( $row ) . ')';
 801                                 }
 802                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 803                         } else {
 804                                 $res = true;
 805                                 $origsql = $sql;
 806                                 foreach ( $args as $row ) {
 807                                         $tempsql = $origsql;
 808                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 809
 810                                         if ( $savepoint ) {
 811                                                 $savepoint->savepoint();
 812                                         }
 813
 814                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 815
 816                                         if ( $savepoint ) {
 817                                                 $bar = pg_result_error( $this->mLastResult );
 818                                                 if ( $bar != false ) {
 819                                                         $savepoint->rollback();
 820                                                 } else {
 821                                                         $savepoint->release();
 822                                                         $numrowsinserted++;
 823                                                 }
 824                                         }
 825
 826                                         // If any of them fail, we fail overall for this function call
 827                                         // Note that this will be ignored if IGNORE is set
 828                                         if ( !$tempres ) {
 829                                                 $res = false;
 830                                         }
 831                                 }
 832                         }
 833                 } else {
 834                         // Not multi, just a lone insert
 835                         if ( $savepoint ) {
 836                                 $savepoint->savepoint();
 837                         }
 838
 839                         $sql .= '(' . $this->makeList( $args ) . ')';
 840                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 841                         if ( $savepoint ) {
 842                                 $bar = pg_result_error( $this->mLastResult );
 843                                 if ( $bar != false ) {
 844                                         $savepoint->rollback();
 845                                 } else {
 846                                         $savepoint->release();
 847                                         $numrowsinserted++;
 848                                 }
 849                         }
 850                 }
 851                 if ( $savepoint ) {
 852                         error_reporting( $olde );
 853                         $savepoint->commit();
 854
 855                         // Set the affected row count for the whole operation
 856                         $this->mAffectedRows = $numrowsinserted;
 857
 858                         // IGNORE always returns true
 859                         return true;
 860                 }
 861
 862                 return $res;
 863         }
 864
 865         /**
 866          * INSERT SELECT wrapper
 867          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 868          * Source items may be literals rather then field names, but strings should
 869          * be quoted with Database::addQuotes()
 870          * $conds may be "*" to copy the whole table
 871          * srcTable may be an array of tables.
 872          * @todo FIXME: Implement this a little better (seperate select/insert)?
 873          *
 874          * @param string $destTable
 875          * @param array|string $srcTable
 876          * @param array $varMap
 877          * @param array $conds
 878          * @param string $fname
 879          * @param array $insertOptions
 880          * @param array $selectOptions
 881          * @return bool
 882          */
 883         function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 884                 $insertOptions = [], $selectOptions = [] ) {
 885                 $destTable = $this->tableName( $destTable );
 886
 887                 if ( !is_array( $insertOptions ) ) {
 888                         $insertOptions = [ $insertOptions ];
 889                 }
 890
 891                 /*
 892                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 893                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 894                  */
 895                 $savepoint = null;
 896                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 897                         $savepoint = new SavepointPostgres( $this, 'mw' );
 898                         $olde = error_reporting( 0 );
 899                         $numrowsinserted = 0;
 900                         $savepoint->savepoint();
 901                 }
 902
 903                 if ( !is_array( $selectOptions ) ) {
 904                         $selectOptions = [ $selectOptions ];
 905                 }
 906                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 907                         $this->makeSelectOptions( $selectOptions );
 908                 if ( is_array( $srcTable ) ) {
 909                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
 910                 } else {
 911                         $srcTable = $this->tableName( $srcTable );
 912                 }
 913
 914                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 915                         " SELECT $startOpts " . implode( ',', $varMap ) .
 916                         " FROM $srcTable $useIndex $ignoreIndex ";
 917
 918                 if ( $conds != '*' ) {
 919                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 920                 }
 921
 922                 $sql .= " $tailOpts";
 923
 924                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 925                 if ( $savepoint ) {
 926                         $bar = pg_result_error( $this->mLastResult );
 927                         if ( $bar != false ) {
 928                                 $savepoint->rollback();
 929                         } else {
 930                                 $savepoint->release();
 931                                 $numrowsinserted++;
 932                         }
 933                         error_reporting( $olde );
 934                         $savepoint->commit();
 935
 936                         // Set the affected row count for the whole operation
 937                         $this->mAffectedRows = $numrowsinserted;
 938
 939                         // IGNORE always returns true
 940                         return true;
 941                 }
 942
 943                 return $res;
 944         }
 945
 946         function tableName( $name, $format = 'quoted' ) {
 947                 # Replace reserved words with better ones
 948                 switch ( $name ) {
 949                         case 'user':
 950                                 return $this->realTableName( 'mwuser', $format );
 951                         case 'text':
 952                                 return $this->realTableName( 'pagecontent', $format );
 953                         default:
 954                                 return $this->realTableName( $name, $format );
 955                 }
 956         }
 957
 958         /* Don't cheat on installer */
 959         function realTableName( $name, $format = 'quoted' ) {
 960                 return parent::tableName( $name, $format );
 961         }
 962
 963         /**
 964          * Return the next in a sequence, save the value for retrieval via insertId()
 965          *
 966          * @param string $seqName
 967          * @return int|null
 968          */
 969         function nextSequenceValue( $seqName ) {
 970                 $safeseq = str_replace( "'", "''", $seqName );
 971                 $res = $this->query( "SELECT nextval('$safeseq')" );
 972                 $row = $this->fetchRow( $res );
 973                 $this->mInsertId = $row[0];
 974
 975                 return $this->mInsertId;
 976         }
 977
 978         /**
 979          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 980          *
 981          * @param string $seqName
 982          * @return int
 983          */
 984         function currentSequenceValue( $seqName ) {
 985                 $safeseq = str_replace( "'", "''", $seqName );
 986                 $res = $this->query( "SELECT currval('$safeseq')" );
 987                 $row = $this->fetchRow( $res );
 988                 $currval = $row[0];
 989
 990                 return $currval;
 991         }
 992
 993         # Returns the size of a text field, or -1 for "unlimited"
 994         function textFieldSize( $table, $field ) {
 995                 $table = $this->tableName( $table );
 996                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 997                         FROM pg_class c, pg_attribute a, pg_type t
 998                         WHERE relname='$table' AND a.attrelid=c.oid AND
 999                                 a.atttypid=t.oid and a.attname='$field'";
1000                 $res = $this->query( $sql );
1001                 $row = $this->fetchObject( $res );
1002                 if ( $row->ftype == 'varchar' ) {
1003                         $size = $row->size - 4;
1004                 } else {
1005                         $size = $row->size;
1006                 }
1007
1008                 return $size;
1009         }
1010
1011         function limitResult( $sql, $limit, $offset = false ) {
1012                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
1013         }
1014
1015         function wasDeadlock() {
1016                 return $this->lastErrno() == '40P01';
1017         }
1018
1019         function duplicateTableStructure( $oldName, $newName, $temporary = false, $fname = __METHOD__ ) {
1020                 $newName = $this->addIdentifierQuotes( $newName );
1021                 $oldName = $this->addIdentifierQuotes( $oldName );
1022
1023                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
1024                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
1025         }
1026
1027         function listTables( $prefix = null, $fname = __METHOD__ ) {
1028                 $eschema = $this->addQuotes( $this->getCoreSchema() );
1029                 $result = $this->query( "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
1030                 $endArray = [];
1031
1032                 foreach ( $result as $table ) {
1033                         $vars = get_object_vars( $table );
1034                         $table = array_pop( $vars );
1035                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1036                                 $endArray[] = $table;
1037                         }
1038                 }
1039
1040                 return $endArray;
1041         }
1042
1043         function timestamp( $ts = 0 ) {
1044                 return wfTimestamp( TS_POSTGRES, $ts );
1045         }
1046
1047         /**
1048          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
1049          * to http://www.php.net/manual/en/ref.pgsql.php
1050          *
1051          * Parsing a postgres array can be a tricky problem, he's my
1052          * take on this, it handles multi-dimensional arrays plus
1053          * escaping using a nasty regexp to determine the limits of each
1054          * data-item.
1055          *
1056          * This should really be handled by PHP PostgreSQL module
1057          *
1058          * @since 1.19
1059          * @param string $text Postgreql array returned in a text form like {a,b}
1060          * @param string $output
1061          * @param int $limit
1062          * @param int $offset
1063          * @return string
1064          */
1065         function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
1066                 if ( false === $limit ) {
1067                         $limit = strlen( $text ) - 1;
1068                         $output = [];
1069                 }
1070                 if ( '{}' == $text ) {
1071                         return $output;
1072                 }
1073                 do {
1074                         if ( '{' != $text[$offset] ) {
1075                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
1076                                         $text, $match, 0, $offset );
1077                                 $offset += strlen( $match[0] );
1078                                 $output[] = ( '"' != $match[1][0]
1079                                         ? $match[1]
1080                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
1081                                 if ( '},' == $match[3] ) {
1082                                         return $output;
1083                                 }
1084                         } else {
1085                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
1086                         }
1087                 } while ( $limit > $offset );
1088
1089                 return $output;
1090         }
1091
1092         /**
1093          * Return aggregated value function call
1094          * @param array $valuedata
1095          * @param string $valuename
1096          * @return array
1097          */
1098         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1099                 return $valuedata;
1100         }
1101
1102         /**
1103          * @return string Wikitext of a link to the server software's web site
1104          */
1105         public function getSoftwareLink() {
1106                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
1107         }
1108
1109         /**
1110          * Return current schema (executes SELECT current_schema())
1111          * Needs transaction
1112          *
1113          * @since 1.19
1114          * @return string Default schema for the current session
1115          */
1116         function getCurrentSchema() {
1117                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
1118                 $row = $this->fetchRow( $res );
1119
1120                 return $row[0];
1121         }
1122
1123         /**
1124          * Return list of schemas which are accessible without schema name
1125          * This is list does not contain magic keywords like "$user"
1126          * Needs transaction
1127          *
1128          * @see getSearchPath()
1129          * @see setSearchPath()
1130          * @since 1.19
1131          * @return array List of actual schemas for the current sesson
1132          */
1133         function getSchemas() {
1134                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
1135                 $row = $this->fetchRow( $res );
1136                 $schemas = [];
1137
1138                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
1139
1140                 return $this->pg_array_parse( $row[0], $schemas );
1141         }
1142
1143         /**
1144          * Return search patch for schemas
1145          * This is different from getSchemas() since it contain magic keywords
1146          * (like "$user").
1147          * Needs transaction
1148          *
1149          * @since 1.19
1150          * @return array How to search for table names schemas for the current user
1151          */
1152         function getSearchPath() {
1153                 $res = $this->query( "SHOW search_path", __METHOD__ );
1154                 $row = $this->fetchRow( $res );
1155
1156                 /* PostgreSQL returns SHOW values as strings */
1157
1158                 return explode( ",", $row[0] );
1159         }
1160
1161         /**
1162          * Update search_path, values should already be sanitized
1163          * Values may contain magic keywords like "$user"
1164          * @since 1.19
1165          *
1166          * @param array $search_path List of schemas to be searched by default
1167          */
1168         function setSearchPath( $search_path ) {
1169                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
1170         }
1171
1172         /**
1173          * Determine default schema for MediaWiki core
1174          * Adjust this session schema search path if desired schema exists
1175          * and is not alread there.
1176          *
1177          * We need to have name of the core schema stored to be able
1178          * to query database metadata.
1179          *
1180          * This will be also called by the installer after the schema is created
1181          *
1182          * @since 1.19
1183          *
1184          * @param string $desiredSchema
1185          */
1186         function determineCoreSchema( $desiredSchema ) {
1187                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
1188                 if ( $this->schemaExists( $desiredSchema ) ) {
1189                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
1190                                 $this->mCoreSchema = $desiredSchema;
1191                                 wfDebug( "Schema \"" . $desiredSchema . "\" already in the search path\n" );
1192                         } else {
1193                                 /**
1194                                  * Prepend our schema (e.g. 'mediawiki') in front
1195                                  * of the search path
1196                                  * Fixes bug 15816
1197                                  */
1198                                 $search_path = $this->getSearchPath();
1199                                 array_unshift( $search_path,
1200                                         $this->addIdentifierQuotes( $desiredSchema ) );
1201                                 $this->setSearchPath( $search_path );
1202                                 $this->mCoreSchema = $desiredSchema;
1203                                 wfDebug( "Schema \"" . $desiredSchema . "\" added to the search path\n" );
1204                         }
1205                 } else {
1206                         $this->mCoreSchema = $this->getCurrentSchema();
1207                         wfDebug( "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1208                                 $this->mCoreSchema . "\"\n" );
1209                 }
1210                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1211                 $this->commit( __METHOD__ );
1212         }
1213
1214         /**
1215          * Return schema name fore core MediaWiki tables
1216          *
1217          * @since 1.19
1218          * @return string Core schema name
1219          */
1220         function getCoreSchema() {
1221                 return $this->mCoreSchema;
1222         }
1223
1224         /**
1225          * @return string Version information from the database
1226          */
1227         function getServerVersion() {
1228                 if ( !isset( $this->numericVersion ) ) {
1229                         $versionInfo = pg_version( $this->mConn );
1230                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1231                                 // Old client, abort install
1232                                 $this->numericVersion = '7.3 or earlier';
1233                         } elseif ( isset( $versionInfo['server'] ) ) {
1234                                 // Normal client
1235                                 $this->numericVersion = $versionInfo['server'];
1236                         } else {
1237                                 // Bug 16937: broken pgsql extension from PHP<5.3
1238                                 $this->numericVersion = pg_parameter_status( $this->mConn, 'server_version' );
1239                         }
1240                 }
1241
1242                 return $this->numericVersion;
1243         }
1244
1245         /**
1246          * Query whether a given relation exists (in the given schema, or the
1247          * default mw one if not given)
1248          * @param string $table
1249          * @param array|string $types
1250          * @param bool|string $schema
1251          * @return bool
1252          */
1253         function relationExists( $table, $types, $schema = false ) {
1254                 if ( !is_array( $types ) ) {
1255                         $types = [ $types ];
1256                 }
1257                 if ( !$schema ) {
1258                         $schema = $this->getCoreSchema();
1259                 }
1260                 $table = $this->realTableName( $table, 'raw' );
1261                 $etable = $this->addQuotes( $table );
1262                 $eschema = $this->addQuotes( $schema );
1263                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1264                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1265                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1266                 $res = $this->query( $sql );
1267                 $count = $res ? $res->numRows() : 0;
1268
1269                 return (bool)$count;
1270         }
1271
1272         /**
1273          * For backward compatibility, this function checks both tables and
1274          * views.
1275          * @param string $table
1276          * @param string $fname
1277          * @param bool|string $schema
1278          * @return bool
1279          */
1280         function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1281                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1282         }
1283
1284         function sequenceExists( $sequence, $schema = false ) {
1285                 return $this->relationExists( $sequence, 'S', $schema );
1286         }
1287
1288         function triggerExists( $table, $trigger ) {
1289                 $q = <<<SQL
1290         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1291                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1292                           AND tgrelid=pg_class.oid
1293                           AND nspname=%s AND relname=%s AND tgname=%s
1294 SQL;
1295                 $res = $this->query(
1296                         sprintf(
1297                                 $q,
1298                                 $this->addQuotes( $this->getCoreSchema() ),
1299                                 $this->addQuotes( $table ),
1300                                 $this->addQuotes( $trigger )
1301                         )
1302                 );
1303                 if ( !$res ) {
1304                         return null;
1305                 }
1306                 $rows = $res->numRows();
1307
1308                 return $rows;
1309         }
1310
1311         function ruleExists( $table, $rule ) {
1312                 $exists = $this->selectField( 'pg_rules', 'rulename',
1313                         [
1314                                 'rulename' => $rule,
1315                                 'tablename' => $table,
1316                                 'schemaname' => $this->getCoreSchema()
1317                         ]
1318                 );
1319
1320                 return $exists === $rule;
1321         }
1322
1323         function constraintExists( $table, $constraint ) {
1324                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1325                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1326                         $this->addQuotes( $this->getCoreSchema() ),
1327                         $this->addQuotes( $table ),
1328                         $this->addQuotes( $constraint )
1329                 );
1330                 $res = $this->query( $sql );
1331                 if ( !$res ) {
1332                         return null;
1333                 }
1334                 $rows = $res->numRows();
1335
1336                 return $rows;
1337         }
1338
1339         /**
1340          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1341          * @param string $schema
1342          * @return bool
1343          */
1344         function schemaExists( $schema ) {
1345                 $exists = $this->selectField( '"pg_catalog"."pg_namespace"', 1,
1346                         [ 'nspname' => $schema ], __METHOD__ );
1347
1348                 return (bool)$exists;
1349         }
1350
1351         /**
1352          * Returns true if a given role (i.e. user) exists, false otherwise.
1353          * @param string $roleName
1354          * @return bool
1355          */
1356         function roleExists( $roleName ) {
1357                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1358                         [ 'rolname' => $roleName ], __METHOD__ );
1359
1360                 return (bool)$exists;
1361         }
1362
1363         /**
1364          * @var string $table
1365          * @var string $field
1366          * @return PostgresField|null
1367          */
1368         function fieldInfo( $table, $field ) {
1369                 return PostgresField::fromText( $this, $table, $field );
1370         }
1371
1372         /**
1373          * pg_field_type() wrapper
1374          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1375          * @param int $index Field number, starting from 0
1376          * @return string
1377          */
1378         function fieldType( $res, $index ) {
1379                 if ( $res instanceof ResultWrapper ) {
1380                         $res = $res->result;
1381                 }
1382
1383                 return pg_field_type( $res, $index );
1384         }
1385
1386         /**
1387          * @param string $b
1388          * @return Blob
1389          */
1390         function encodeBlob( $b ) {
1391                 return new PostgresBlob( pg_escape_bytea( $b ) );
1392         }
1393
1394         function decodeBlob( $b ) {
1395                 if ( $b instanceof PostgresBlob ) {
1396                         $b = $b->fetch();
1397                 } elseif ( $b instanceof Blob ) {
1398                         return $b->fetch();
1399                 }
1400
1401                 return pg_unescape_bytea( $b );
1402         }
1403
1404         function strencode( $s ) {
1405                 // Should not be called by us
1406
1407                 return pg_escape_string( $this->mConn, $s );
1408         }
1409
1410         /**
1411          * @param null|bool|Blob $s
1412          * @return int|string
1413          */
1414         function addQuotes( $s ) {
1415                 if ( is_null( $s ) ) {
1416                         return 'NULL';
1417                 } elseif ( is_bool( $s ) ) {
1418                         return intval( $s );
1419                 } elseif ( $s instanceof Blob ) {
1420                         if ( $s instanceof PostgresBlob ) {
1421                                 $s = $s->fetch();
1422                         } else {
1423                                 $s = pg_escape_bytea( $this->mConn, $s->fetch() );
1424                         }
1425                         return "'$s'";
1426                 }
1427
1428                 return "'" . pg_escape_string( $this->mConn, $s ) . "'";
1429         }
1430
1431         /**
1432          * Postgres specific version of replaceVars.
1433          * Calls the parent version in Database.php
1434          *
1435          * @param string $ins SQL string, read from a stream (usually tables.sql)
1436          * @return string SQL string
1437          */
1438         protected function replaceVars( $ins ) {
1439                 $ins = parent::replaceVars( $ins );
1440
1441                 if ( $this->numericVersion >= 8.3 ) {
1442                         // Thanks for not providing backwards-compatibility, 8.3
1443                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1444                 }
1445
1446                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1447                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1448                 }
1449
1450                 return $ins;
1451         }
1452
1453         /**
1454          * Various select options
1455          *
1456          * @param array $options An associative array of options to be turned into
1457          *   an SQL query, valid keys are listed in the function.
1458          * @return array
1459          */
1460         function makeSelectOptions( $options ) {
1461                 $preLimitTail = $postLimitTail = '';
1462                 $startOpts = $useIndex = $ignoreIndex = '';
1463
1464                 $noKeyOptions = [];
1465                 foreach ( $options as $key => $option ) {
1466                         if ( is_numeric( $key ) ) {
1467                                 $noKeyOptions[$option] = true;
1468                         }
1469                 }
1470
1471                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1472
1473                 $preLimitTail .= $this->makeOrderBy( $options );
1474
1475                 // if ( isset( $options['LIMIT'] ) ) {
1476                 //      $tailOpts .= $this->limitResult( '', $options['LIMIT'],
1477                 //              isset( $options['OFFSET'] ) ? $options['OFFSET']
1478                 //              : false );
1479                 // }
1480
1481                 if ( isset( $options['FOR UPDATE'] ) ) {
1482                         $postLimitTail .= ' FOR UPDATE OF ' .
1483                                 implode( ', ', array_map( [ &$this, 'tableName' ], $options['FOR UPDATE'] ) );
1484                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1485                         $postLimitTail .= ' FOR UPDATE';
1486                 }
1487
1488                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1489                         $startOpts .= 'DISTINCT';
1490                 }
1491
1492                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1493         }
1494
1495         function getDBname() {
1496                 return $this->mDBname;
1497         }
1498
1499         function getServer() {
1500                 return $this->mServer;
1501         }
1502
1503         function buildConcat( $stringList ) {
1504                 return implode( ' || ', $stringList );
1505         }
1506
1507         public function buildGroupConcatField(
1508                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1509         ) {
1510                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1511
1512                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1513         }
1514
1515         /**
1516          * @param string $field Field or column to cast
1517          * @return string
1518          * @since 1.28
1519          */
1520         public function buildStringCast( $field ) {
1521                 return $field . '::text';
1522         }
1523
1524         public function streamStatementEnd( &$sql, &$newLine ) {
1525                 # Allow dollar quoting for function declarations
1526                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1527                         if ( $this->delimiter ) {
1528                                 $this->delimiter = false;
1529                         } else {
1530                                 $this->delimiter = ';';
1531                         }
1532                 }
1533
1534                 return parent::streamStatementEnd( $sql, $newLine );
1535         }
1536
1537         /**
1538          * Check to see if a named lock is available. This is non-blocking.
1539          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1540          *
1541          * @param string $lockName Name of lock to poll
1542          * @param string $method Name of method calling us
1543          * @return bool
1544          * @since 1.20
1545          */
1546         public function lockIsFree( $lockName, $method ) {
1547                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1548                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1549                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1550                 $row = $this->fetchObject( $result );
1551
1552                 return ( $row->lockstatus === 't' );
1553         }
1554
1555         /**
1556          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1557          * @param string $lockName
1558          * @param string $method
1559          * @param int $timeout
1560          * @return bool
1561          */
1562         public function lock( $lockName, $method, $timeout = 5 ) {
1563                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1564                 $loop = new WaitConditionLoop(
1565                         function () use ( $lockName, $key, $timeout, $method ) {
1566                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1567                                 $row = $this->fetchObject( $res );
1568                                 if ( $row->lockstatus === 't' ) {
1569                                         parent::lock( $lockName, $method, $timeout ); // record
1570                                         return true;
1571                                 }
1572
1573                                 return WaitConditionLoop::CONDITION_CONTINUE;
1574                         },
1575                         $timeout
1576                 );
1577
1578                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1579         }
1580
1581         /**
1582          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKSFROM
1583          * PG DOCS: http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1584          * @param string $lockName
1585          * @param string $method
1586          * @return bool
1587          */
1588         public function unlock( $lockName, $method ) {
1589                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1590                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1591                 $row = $this->fetchObject( $result );
1592
1593                 if ( $row->lockstatus === 't' ) {
1594                         parent::unlock( $lockName, $method ); // record
1595                         return true;
1596                 }
1597
1598                 wfDebug( __METHOD__ . " failed to release lock\n" );
1599
1600                 return false;
1601         }
1602
1603         /**
1604          * @param string $lockName
1605          * @return string Integer
1606          */
1607         private function bigintFromLockName( $lockName ) {
1608                 return Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1609         }
1610 } // end DatabasePostgres class